We are continuing our studies on the biological role of polyamines. Particular attention is being directed towards the selection of Escherichia coli and yeast mutants that are defective in the biosynthesis of these amines, and a study of the resultant phenotypic effects. We are also studying the control of polyamine biosynthesis in the yeast mutants. We are preparing stable, multicopy plasmids which contain the various E. coli genes involved in biosynthesis of the amines, in order to obtain large amounts of the enzymes for study of the protein and cofactors involved. We have purified and are studying the mechanism of action and the structure of the adenosylmethionine synthetase of E. coli. We are purifying the ornithine decarboxylase of Saccharomyces cerevisiae from a derepressed strain, to study its control.